President Obama chose the most controversial of his potential nominees to the Supreme Court, and he presented Judge Sonia Sotomayor yesterday as the embodiment of the qualities he seeks in a judge: a rigorous intellect, an appreciation of the limited role of the judiciary and "an understanding of how the world works and how ordinary people live."

Obama never used the word "empathy." But he held fast to the notion, noxious to conservatives and challenging to some Democrats, that some of the answers to the most complicated legal questions come from life's experiences as well as the lawbooks.

The idea has been more clearly articulated by Obama than any president before him, and could create a different and perhaps more complicated confirmation process. It seems far different from Chief Justice John G. Roberts Jr.'s insistence at his confirmation that the role of a judge is to be like an umpire, calling balls and strikes.

Obama, who as a senator voted against Roberts, made clear he sees the role differently.

"Experience being tested by obstacles and barriers, by hardship and misfortune; experience insisting, persisting, and ultimately overcoming those barriers . . . is a necessary ingredient in the kind of justice we need on the Supreme Court," Obama told the nation and an East Room filled with supporters and family, including Sotomayor's tearful mother Celine, who moved to New York from Puerto Rico in the 1940s.

Sotomayor, 54, who would become the court's first Latina and only the third woman to serve among what would be 111 justices in the court's history, picked up the theme.

"This wealth of experiences, personal and professional, have helped me appreciate the variety of perspectives that present themselves in every case that I hear," said Sotomayor, who has served as a district judge and is currently on the U.S. Court of Appeals for the 2nd Circuit in New York.

"I strive never to forget the real-world consequences of my decisions on individuals, businesses and government."

3 Others Interviewed

Obama chose Sotomayor, who has drawn the most fire from conservative legal activists because of her outspoken statements on role, gender and ethnicity, after interviewing her Thursday and thinking about it over the holiday weekend. He also interviewed Judge Diane P. Wood of the U.S. Court of Appeals for the 7th Circuit; Solicitor General Elena Kagan; and Homeland Security Secretary and former Arizona governor Janet Napolitano.

Obama was more familiar with the latter three: Wood is well-known in Chicago's liberal legal establishment, where she enjoys celebrity status, and the president had placed both Napolitano and Kagan in his administration.

He spent an hour with Sotomayor, part of more than seven hours she spent at the White House that day meeting with advisers who were helping him make the critical decision. A senior White House official said the face-to-face meeting was a "key moment" and that Obama emerged to tell aides that he was especially impressed with the breadth of Sotomayor's experience.

That was something White House officials stressed yesterday: that she has worked as a prosecutor and corporate litigator, and has spent more time on the federal bench than any of the current justices when they were appointed.